Trouble Shooting Flow Chart - ViewSonic G90fB-4 Service Manual

6. Trouble Shooting Flow Chart

6-1. No raster,CRT relative circuit problems
CHECK MAIN BOARD
SUPPLY: 12V, 180V, 83V, -12V, 6.3V
PLEASE CHECK HIGH VOLTAGE OF
CRT ABOUT 25.5~26.5KV
OK
CHECK THE HEATER VOLTAGE AT
CRT SOCKET ABOUT 6.3V
OK
CHECK G2 VOLTAGE ABOUT 550~650V
OK
CHECK THE G1 VOLTAGE ABOUT –16V
AT BRIGHTNESS MAX
OK
CHECK THE CATHODE
ABOUT 60V
6-2. Abnormal DDC (Plug & Play)
CHECK IC101 PIN 16 VOLTAGE ABOUT 5V
NG
OK
CHECK SIGNAL CABLE
OR H802 PIN 2, 4 DATA OUTPUT
ViewSonic Corporation
POWER
OK
NG
NG
OK
VOLTAGE
NG
PLEASE CHECK POWER SAVING
CIRCUIT OR
CIRCUIT.
ENTER POWER OR POWER CIRCUIT
FAIL.
CHECK THE CIRCUIT OF PIN 18/20 OF
IC101
CHECK THE 6.3V SUPPLY CIRCUIT:
Q906,ZD902
NG
CHECK FBT
CHECK THE G1 CONTROL CIRCUIT:
NG
Q705 RELATIVE CIRCUIT
CRT FAIL
CHECK IC902 GOOD OR FAIL
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17
POWER SUPPLY
NG
G90fB-4